I smell BS! This tenant seems to have no idea what she's talking about. A service dog has been trained since it was a puppy to be a working dog. These dogs are immaculately trained and certified to handle nearly all situations and obey commands religiously. Put bulls are almost never service dogs. There are different dog breeds that are preferred for different issues. Therapy, physical assistance, and diabetes dogs are generally Labradors. A service dog is much, much different than an emotional support animal.
Tenantresourcecenter: "Landlords can only deny the service animal or emotional support animal if:
- the tenant is not disabled or does not have a disability-related need
- the tenant fails to provide requested documentation allowed by this law
- there is undue financial or administrative burden or would fundamentally change the services provided
- the specific animal “poses a direct threat to a person's health or safety” that cannot be reduced or eliminated by another accommodation
- the specific animal would cause substantial physical damage to the property that can’t be reduced or eliminated by another accommodation. Wis. Stat. 106.50(2r)(bg)4.d., Wis. Stat. 106.50(2r), 2017 Wis. Act 317, Sec. 30"
Wis Stat: 2. "If an individual keeps or is seeking to keep an animal that is individually trained to do work or perform tasks in housing, an owner, lessor, lessor's agent, owner's agent, or representative of a condominium association may request that the individual submit to the owner, lessor, agent, or representative reliable documentation that the individual has a disability and reliable documentation of the disability-related need for the animal, unless the disability is readily apparent or known. If the disability is readily apparent or known but the disability-related need for the animal is not, the individual may be requested to submit reliable documentation of the disability-related need for the animal."
Obviously those are Wisconsin laws, check your Arkansas statutes before taking any action. If you deny for any of those reasons be prepared to back up your case in court.
On a side note: get rid of the pet deposit and charge $40 or $50 per month in pet rent for dogs. It doesn't get returned when they leave, and that will go a lot further than a measly $50 deposit. $50 won't even barely cover a scratched up door from an excited dog as it's parent gets home.